Volatile sulfur preparation of green lixiviant thiosulfate: Generating mechanism and application in gold extraction

The high consumption of the outstanding non-cyanide lixiviant, thiosulphate, has been a technical bottleneck hindering its industrial application. The self-generation of thiosulphate from sulfur-containing minerals at atmospheric pressure can solve this technical bottleneck, but this process will inevitably cause the volatilization of sulfur, which makes the sulfur utilization lower. Excitingly, this paper has achieved the production of thiosulphate from volatile sulfur as described above and successfully applied it to the entire gold extraction process. Hence, this manuscript initially elucidates the process mechanism of thiosulfate derived from volatile sulfur, achieving a thiosulfate concentration of 0.44 M with optimal process parameters. Additionally, the sulfur migration pathway is S → S2O32− → S4O62− → S3O62− → SO32− → SO42−. Subsequently, the generation kinetics fitting results suggest that the oxidation process is controlled by different surface chemical reactions (30 → 70 °C: Ea = 41.06 kJ/mol, 70 → 80 °C: Ea = 37.61 kJ/mol). Furthermore, a gold extraction percentage of 87.23 % was achieved. Then, 99.41 % of copper and 98.63 % of gold were effectively desorbed from the loaded resin in the actual pregnant solution, respectively. This fruitful research has opened up another promising avenue for the generation of thiosulfate at atmospheric pressure, achieving high-value utilization of sulfur in sulfur-containing minerals and significantly advancing the commercialization of non-cyanide gold extraction using self-generated thiosulfate.